Ortho-tolidine phosphoramidate corrosion inhibitor



The benzidine Salt of diamid0 dii!nid0riph0sphoric acd was prepared as fouows To a Solution of 1-84 g' 0f benzidine in 122 ml water and 61 ml. 0f acetic acid wa3 SWly added a Solution of l 00 g. 0f the trisodiun1 diamid0 diimid0riph0sphate in 100 ml. water After stirring for an hour the crystalline precipitate was tered 0 and washed with alcohol and ether Na H The benzidine Sat of diin1idotriph0sphoric acid vas prepared aS f010ws( 'I'0 a S()ll1[ion of l(84 g of benzidine in 122 ml. water and 61 Inl. 0f acetic acid Was Slowly added a soution of 1.00 g of the tris()dium dihydrogen diimid0triphosphate in 100 ml. water After Stirring for an hour he crystanine precipitate was fltered 0 and Washed With alc0h0 and ether The utiy of the 0-0idine salt of phosphoramidic acid as a corrosion inhibitor was demonstrated by re paring a Series of suspensions Tespecivey containing: I 2%; II 0.); III, 0.1% by weight of the 0-tolidine salt of ph0sphoran1idic acid Another s01ution, IV containing only water Was emp0yed as a contro in the tests. The four S0utions were placed in test tubes into which sman 0Hshed Samples of mild Stee Were placed' It was observed that at the end of 24 hours the thee S0]utions, I, II and III, containing he alTine Salt 0f phosphorarnidic acid exhibited Substantialy T10 rLlsting of the steel, While the contr( S()Llion, IV, indicated Subsan...al Tusting of the specin1en.

In general, it has been found that aqueous or organic Solutions or dispersions containing fron1 0-01...) to j%) by weight of the amine salt are useful for corrosion inhibition what is claimed is:

Process for reducing the corrosion of ferrous netas which corn rSeS contacting the Said metal with water in the presence 0f O'0id...ne ph08phoranidate] Refereuces ced in the me 0f this patent UNITED STATES PATENTS 2,7j,l56 Marsh July 17 196 Z,757,066 Gardner July 3l 1956 2,776,3ll Erbel et al Jan l, l97 2,786,07 Krase et al Mar. 19, l9j7 0THER REFERENCES I 0S0ap0ff: ()rgan0-Ph0sphorus Co!npounds, Iohn Wuey, New York, 19jo, pp 28328S 288 29SZ97, 319. 

1. PROCESS FOR REDUCING THE CORROSION OF FERROUS METALS WHICH COMPRISES CONTACTING THE SAID METAL WITH WATER IN THE PRESENCE OF O-TOLIDINE PHOSPHORAMIDATE. 